Safety

The Combo V2 board (at the time of writing, 12th of October 2024) doesn’t ship with any protection board for the USB connection to your Pi. If you plug it directly in to the USB ports of your Pi there is a risk that if something goes wrong with your wiring (it gets caught up or damaged or cracks or whatever) then there could be a voltage spike that has the potential to damage the USB circuitry on the Raspberry Pi, stopping the USB from working or destroying the Pi outright.

I have done further testing with this board, trying to induce failure through disconnecting the GND/24v/USB, and hotplugging the XT30, but nothing I’ve done has been able to damage either the SB Combo v2 or the Pi it was attached to (without an isolator).

This is by no means a guarantee, but also it is likely the implementation on the Combo V2 board is robust enough to be unlikely to cause damage.

It still may be worth including an Isolator board as below just in the off chance something fails and bridges 24v to USB. It’s an unlikely scenario, but an isolotor would protect the Pi if it did happen. And 8 bucks or so is pretty cheap insurance.

I will keep the below information available if you wish to add this extra protection to your system.

A simple solution I’ve found is an isolation board using the ADUM3160 usb isolator chip. They are pretty cheap (around 9 Australian dollars) and no doubt they can be found in all the usual online marketplaces.

USB Mode

To put the SB Combo V2 board into USB mode (instead of CANBUS mode) make sure the two switches are in the “down” position.

DFU Mode

To put the SB Combo V2 into DFU mode, connect it via USB to the Pi (either by the main cable, or by the USB-C port) then hold the BOOT0 button, press and release the RESET button, then count to 5 and release the BOOT0 button.

Katapult Config

Klipper Config

Sample Config

A sample config file can be found at https://github.com/FYSETC/SB_Combo_V2/tree/main/Config

More Info

More information can be found at the SB Combo V2 wiki